By Kimberly Toscano
Shrubs bring pizazz to container plantings with seasonal bursts of color, stoic structure, and stunning foliage. But the life span of a container planting is often limited. In this three-step plan, shrubs take on changing roles in containers until finally finding a home in the garden. The final step might convert hesitant gardeners who are resistant to relegating long-lived shrubs to containers.
1. Add a Thrill to Mixed Containers
Shrubs make ideal “thrillers” in the classic thriller-filler-spiller container recipe. Young shrubs are perfect for use in mixed containers, as their smaller size allows room for companion plants. Upright shrubs like ‘Orange Rocket’ Barberry and Twist of Pink™Variegated Oleander work well in the role of thriller.
Many container-worthy shrubs can also be cast as fillers or spillers. Purple Pixie® Dwarf Weeping Loropetalum is gorgeous pouring over the edge of a container, while Flirt™ Nandina and ‘Soft Caress’ Mahonia add lush texture as fillers. When selecting plants for mixed containers, think about how their role may change as plants grow over a season or two.
2. Show-off as a Focal Point
After a season or two in a container, many shrubs become too large to grow alongside their companions. At this point, shrubs like Juliet™ Cleyera or Oakland™ Holly might be used solo in containers to provide structural accents or define space. Even low-growing shrubs like Ultra Violet™ Buddleia and Night Light™ Chamaecyparis work well as stand-alone container plantings. Upright shrubs also offer stunning (and portable) focal points.
Try Early Bird™ Purple Crapemyrtle on sunny patios or porches. Many larger shrubs can be grown with perennials spilling over the edges of containers. The coarse foliage of ‘Plum Cascade’ and ‘Redstone Falls’ Heucherellas adds evergreen color and texture to containers.
3. Time to Transplant
After three to five years most shrubs begin to show signs of strain from container life. Stunted growth or reduced flowering indicate it is time to move plants into the garden. This marks the beginning of a new life for your shrub as it finds a home in the landscape. One of the benefits of growing shrubs in containers before planting them out in the garden is that after several seasons, you have become quite familiar with the plant’s characteristics. Perhaps you’ve already found it a perfect place in the garden. Make sure to loosen the root ball when transplanting and dig a wide planting hole to help roots spread out as they establish.
Carefully consider winter hardiness when selecting shrubs to grow year-round in containers. The indicated USDA hardiness zone found on plant labels pertains to plants installed in the ground. Plants in containers experience colder temperatures because the roots are not insulated. Give container plants the best chance of winter survival by selecting varieties that are two zones hardier than where you live. Finally, use a weatherproof container, as terra cotta and many clay pots are prone to cracking when left outdoors over the winter.